Moistureproof material and method



named Sept. 6, 193a UNITED STATES PATENT OFFICE MOISTUBEPBOOI' MATERIALAND METHOD 4 MAKING THE SAME Theron G. Fines] and Donald E. Drew,Kenmore, N. Y., alsignors, by meme asslgnmenta, to E. I. du Pont deNemours & Company, Wilmington, Del., a corporation of Delaware NoDrawing. Original No. 2,108,809, dated Febmay 32, 1038, Serial No.188,443, June 28, 1034. Application for rah-o July 13, 1938, Serial No.

19 Claims.

5 Prior to the instant invention, one of the common procedures forwaxing paper consisted in passing the paper through a bath of moltenparamn and then thereafter setting or fixing the paraffin. The usual waxemployed in these procm esses was of the white crystalline type ofpara!- fln, had a refractive index substantially below that ofcellulose, and resulted in films characterized by considerable haze.Thus, it was impossible to make a paramn-impregnated paper of hightransparency. One of the prior art procedures for setting or fixing thewax adhering to and in the paper comprised chilling the waxed paper bypassing it through cold water. It is, however, to be noted that theimmersion in cold go waterwas not begun until after crystallization ofthe wax had begun. As a consequence, the paraflln film was composed ofvery small crystals which made it impossible for the film to beglass-clear. g The product which was obtained by the prior artprocedures, in addition to being non-transparent, was furthermorecharacterized in that it did not possess the desired flexibility.Additionally, the surface was very easily marred or 30 smeared uponhandling.

We have found that, by treating paper of the type more fully describedherein with a wax composition, the essential ingredients of whichconsist of a moistureprooflng wax or waxy substance, a hard wax and ablending agent in the molten state and thereafter rapidly chilling thewax paper, while the wax composition is still definitely in the moltenstate and before any crystallization has begun, by immersing the same incold water, we can produce a moistureproof and highly transparent paperwhich can be sat isfactorily used as a transparent moistureproofwrapping tissue.

It is therefore an object of the instant inven- 45 tion to provide atransparent and moistureprooi' paper which is suitable for use as atransparent and moistureproof wrapping tissue.

Another object of this invention is to provide a method of producing ahighly transparent and 50 moistureproof paper.

A still further object of this invention is to provide a wax compositionwhich, upon being rapidly chilled while it is definitely in the moltencondition and before crystallizationhas begun,

55 will produce a glass-clear coating which is tough,

flexible, glossy, non-tacky, exhibits no tendency to sticlrtogetherunder ordinary weather conditions, has good surface slip, is dimcultlymarked or smeared by handling, and is free from greas feel, etc.

Other objects will appear from the following description and appendedclaims.

As is apparent from the foregoing objects,

one of the phases of the instant invention contemplates a waxcomposition which, when rapidly chilled, as by being immersed in coldwater, while in the molten condition and bei'oLe any crystallization hasbegun, will produce a coating which is moistureproof, glass-clear intransparency, glossy, tough, flexible, non-toxic, free from odor andtaste, non-greasy, hard, difllcultly marred or smeared on handling,non-tacky, possesses good surface slip, exhibits no tendency to sticktogether under ordinary weather conditions, is capable of beingheat-sealed to a high degree, can be glued by adhesives commonly usedfor Joining moistureproof lacquer surfaces, and can be printed, at leastwith special inks now used for printing moistureproof lacquer surfaces.

For the purposes of this specification and claims, we definemoistureproof materials as those which, in the form of continuous,unbroken sheets or films, permit the passage of not more than 690 gramsof water vapor per 100 square meters per hour, over a period of 24hours, at approximately 39.5" C.:0.5 C., the relative humidity of theatmosphere at one side of the fllm being maintained at least at 98% andthe relative humidity of the atmosphere at the other side beingmaintained at such a value as to give a humidity differential of atleast 95%.

Moistureproofing coating compositions are defined as those which, whenlaid down in the form of a thin, continuous, unbroken film applieduniformly as a coating with a total coating thickness not exceeding0.0005" to both sides of a sheet of regenerated cellulose of thicknessapproximately 0.0009", will produce a coated prodnot which ismolstureproof.

For the purposes of experimental tests, especially for those materialsadaptable as coating compositions, moistureproof materials include thosesubstances, compounds or compositions which, when laid down in the formof a continuous, unbroken film applied uniformly as a coating with atotal coating thickness not exceeding 0.0005" to both sides of a sheetof regenerated cellulose of thickness approximately 0.0009", willproduce a coated sheet which will permit the passage therethrough of notmore than 690 grams of water vapor per 100 square meters per hour over aperiod of approximately 24 hours, at a temperature of 39.5 C.i0.5 C.(preferably 39.5 C.:0.25 C.), with a water vapor pressure differentialof 50-65 mm. (preferably 53.4:031 mm.) of mercury. Fbr convenience, thenumber of grams of water vapor passed under these conditions may bereferred to as the permeability valu An uncoated sheet of regeneratedcellulose having a thickness of approximately 0.0000" will show apermeability value of the order of 6900.

In many cases, the moistureproofness is 20. 30, 40. 50 and up to 100 ormore times better than the untreated paper.

The wax composition consists essentially of a moistureprooiing wax orwaxy substance, a hard wax (either vegetable or animal), and a blendingagent which is generally a resin. As the moistureproflng w iX, we preferthe white crystalline high melting point paraflin wax, such as onehaving a melting point of over 50 C., such as 52 C., 55 0., 60 0., orindeed higher. we may use the amorphous paraiiins, particularly thosehaving a high melting point, to give increased flexibility oi' thecomposition. The low melting, noncrystalline waxes, vasellnes, etc., ifused, will only be in very minor quantities, since they tend to decreasethe moistureproofness of the product and also tend to give a producthaving a greasy and smeary surface.

The hard wax component imparts toughness to the composition. It alsocontributes greatly in producing hard, non-tacky, non-smeary surfaces aswell as strong heat-sealing properties. The hard wax may be a vegetableor animal wax, and, preferably, candelilla wax or carnauba wax. Thesewaxes are generally esters of the higher fatty acids and high molecularweight aliphatic alcohols. As additional illustrative examples may bementioned Montan wax, palm wax, etc. as well as certain synthetic waxesof a similar nature, such as may be produced by esterifying the acids ofMontan wax with the higher alcohols.

The composition of paraflin and hard waxes, while miscible well abovetheir melting points, produce cloudy liquids or semi-solids in theregion of their melting points. This condition is not avoided even byrapid chilling. The blending agent serves to prevent this separation andto inhibit the production of any haziness in the chilled composition. Inother words, the blending agent primarily functions to give the rapidlychilled composition its glass-clear clarity. It may also, of course, bechosen to assist in increasing the flexibility, gloss, non-tackiness,heat-sealing, etc.

In general, as above mentioned, the blending agents are resins. Asseveral illustrative examples of blending agents may be mentioned thecommon varnish or lacquer resins, such as ester gum, elemi, dammarresidue or the resins from gutta percha, or some of the coal tar oranthracene-like resins or some of the synthetic resins like properlymodified alkyd resins; and hydrorosinates including diethylene glycolhydrorosinate.

If desired, other constituents which serve some special purpose, such asimparting greater flexibility to the product, greater slip betweenadjacent surfaces, assisting the resins in preventing blushing,increasing the heat-sealing qualities, etc. may be incorporated in thecomposition. Rubber, gutta percha, balata, etc., when used in smallquantities, impart to the product a greater flexibility and toughness,as well as greater heatseal Joint strength, when the composition iscoated in thin films. Other toughening, agents may be used. such as asuitable cellulose derivate (ethyl cellulose) or small quantities offilm-forming resin, as vinyl acetate resins. For decreasing the tendencyfor blush, small quantities of substances, such as hydrogenated castoroil, paramn oils, hydroxy fatty acids, beta-naphthol, hydronaphthaleneresins, etc., may be used. Greater smoothness or slippage betweenadjacent surfaces is secured when small quantities of talc-likesubstances, such as zinc stearate, are added to the composition.

To increase the penetrating power of the compositions, particularly whenthey contain substances which give them increased viscosity in themolten condition, a small quantity of a volatile solvent, such as toluolor solvent naphthol, may be added to the composition. We prefer to usethese solvents only in limited amount, such as is necessary to give thecomposition the desired fluidity and melting point, whereby it willpenetrate well and/or be applied easily and readily. The amount ofsolvent will generally be approximately equal to the amount of thecomposition or less. The minimum amount of solvent is preferably used inthe interest of saving solvent expense and in saving time required toeliminate the solvents from the impregnated paper.

The practical limits of the ingredients constituting the composition areas follows, the percentages being by weight:

Percent Paraflln wax 2 to 30 Hard wax 20 to Blending agents (resins) 20to 80 It is, of course, impossible to employ every combination ofcomponents within these ranges. Some of the combinations will nottolerate, for example, 30% paraflln. Some of the hard waxes require amuch greater amount of resin to produce glass-clear illms than doescandelilla, but at some point within these limits a coating compositionmay be formulated which will, when processed in accordance with theprinciples of this invention, be transparent, glass-clear and possessthe other desirable properties. Several illustrative compositions aregiven in the specific examples hereinafter set forth.

One of the characteristic features of the compositions contemplated bythe instant invention is that they have an index of refraction close tothat of cellulose. In general, the refractive index of the compositioncan be readily controlled by the kind and quantity of resins used. Forexample, the refractive index of the composition may be increased byadditions of highly refractive resins, of which coumarone andchlorinated diphenyl resins are examples. The compositions are,furthermore, characterized in that in the molten state they have aviscosity higher than that which parailin exhibits in the molten state.This characteristic is highly desirable when the composition is used forcoating purposes. By virtue of this characteristic, it is possible toobtain a more molstureproof product than can be secured with paraillnwax. the consumption of impregnating media being substantially equal orsomewhat less. For example, in transparentizing and moistureproofingpaper, the very small (pinholes) and relatively wide spaces in thesurface of the tissue must be completely bridged by the compositionafter any solvent present has been evaporated to produce a perfectlycontinuous ill surface of the impregnated paper after removal film.Thus, paraflin from a melt or solution, when scraped down to a thin filmon the paper surface, breaks at these pinholes with the result that thefilm is discontinuous. The instant compositions do not have any tendencyto do this.

The compositions hereinbefore set forth are particularly suitable fortransparentizing and moistureproofing thin, porous tissue paper notexceeding 0.002 of an inch in thickness, the fibers of which areinherently transparent, said paper containing no opaque sizing materialnor any substances which destroy the porosity or absorptiveness of thepaper to organic liquids. In the preferred embodiment oftransparentizing and moistureproofing this paper, the latter is highlycalendered, i. e., super-calendered, prior to the impregnation with themolten wax composition. Preferably, also, prior to the calenderingoperation a wetting agent is incorporated in the paper, whereby thespeed of the absorption of the wax composition is increased. The highlycalendered tissue paper containing the wetting agent is then impregnatedwith the selected composition maintained in the molten state. Whenimpregnation is complete. the excess composition is removed in anyconvenient manner, as, for example, with doctor knives, to such anextent that the surface of the paper remains completely covered by afilm oi the molten composition. The thickness of the paper will usuallybe increased about 0.0003 of an inch by the layer of the waxcomposition. The impregnated paper is then cooled, the moltencomposition solidified, and the coated paper wound up.

To clarify the hazy film thus produced, the impregnated paper is passeddown through a suitably selected chamber, in which the wax compositionis completely melted, and then directly into a bath of water at 25 C. orbelow, while the composition in the paper is still completely molten,and before crystallization has begun. When the molten composition comesin contact with the water, it is very quickly solidified and so rapidlybrought through its crystallization point that separation of suchcomponents as are incompatible in the melt near the crystallizationpoint is prevented, with the result that a glossy, haze-free,transparent paper is secured. The transparent paper, after being drawnout of the water, is subjected to suitable devices or treatments whichremove and/or absorb the water. Finally, the film is wound up.

The paper may be impregnated with the seiected composition in many ways.The paper may be passed through the molten composition at such a speedthat upon its emergence from the bath it will be completely impregnated.Instead of keeping the paper in the wax composition melt until it isthoroughly impregnated, the paper may be passed through the meltrapidly, and then impregnation allowed to proceed either before or afterremoving the excess melt, and finally solidifying the composition. Theimpregnated paper may be alternately heated and cooled untilimpregnation is complete.

The melt may be applied to the paper in other ways than by passing thepaper through a tank thereof. It may be applied first to one side of thepaper and then to the other by transfer rolls. It may be applied to bothsides 01' the paper by means of suitable hoppers which apply in oneoperation the correct quantity oi. material necessary for the bestquality of the finished product.

In many cases it is desirable to smooth out the of the excesscomposition by suitable smoothing rods, brushes or polishing rolls. Thisis particularly'so if impregnation is not thoroughly completed beforethe excess melt is removed. If im- Dres'nation goes on after the excesscomposition is removed, certain parts of the paper will absorb more meltthan others and there will result a rough surface unless the surface isin some way smoothed after impregnation is complate.

The impregnated paper, after it leaves the doctor knives or smoothingmils, and while the composition is still in the completely molten state,may be passed directly into cold water without the above-describedintervening cooling operation between impregnation and clarifying. Theadhering water is-removed from the paper after it leaves the chillingbath by any of the known methods, as by squeeze rolls, doctors, airblasts, wiping devices, vacuum apparatus and/r various mechanicalshaking devices or combinations of these devices. For example, thetransparent paper may be drawn out of the water and passed first betweensuitable scraping bars or squeeze rollers and then over felt wiping padswhich absorb the remaining drops of water. Preferably, the water isremoved as quickly and as completely as possible from the coatedtransparent paper, since the water, if allowed to remain, will slowlypenetrate the film and result in white spots in the product.

Instead of chilling the transparent impregnated papers by passagethrough cold water, the hot paper may be passed over positively chilledrolls.

As an additional step in our process, the finished sheet may besubjected to an atmosphere of 60% to 90% relative humidity at 40 C. to60 C. for a sufliciently long time to replace a normal amount ofmoisture in the paper that may have been lost during any previoustreatment in impregnation or clarification. With some compositions, thelower humidifying temperature is preferred, since temperatures highenough to melt the composition result in a blush similar to thatproduced when the composition is not rapidly chilled.

If solvents are used in the composition, the process includes anadditional step. After removal of the excess solution, the impregnatedpaper is passed through a drying chamber at about 60 C. to 100 C. inwhich the solvent is removed. When this drying step is necessary, it isgenerally desirable to humidity the finished transparent paper torestore moisture lost in drying- The compositions and procedureshereinbefore described are also equally applicable in coating sheetingof various types. They may be used for coating glassine paper or anythin, smooth, dense, non-fibrous, substantially non-porous andpreferably transparent sheeting formed of a cellulosic, albuminous orother material, such as, for example, rubber or rubber derivatives. Asillustrative examples of celiuiosic sheeting may be mentioned sheetingcoagulated or precipitated from an aqueous cellulosic dispersion orsolution, for example, sheeting of regenerated cellulose, glycolcellulose, cellulose glycollic acid. lowly etherified or lowlyesterified cellulose, such as lowly methylated cellulose; and sheetingof cellulose derivatives, such as cellulose acetate, cei- Iuiosenitrate, ethyl cellulose, benzyl cellulose, etc. As illustrativeexamples 0! albuminous sheeting may be mentioned gelatin and casein,hardened or not, as desired. Because of the nature of the surfaces,whereby very little impregnation is secured, a very thin coating, suchas 0.00005 of an inch on each side, will give the desired result. Whenthe base sheeting is transparent, the ultimate product will betransparent. Due to the fact that impregnation is not obtained, theincorporation of the wetting agent is omitted.

Hereafter as set forth several illustrative examples of the instantinvention:

Example I (A) A thin, porous sulphite tissue, basis weight between 13pounds and 18 pounds (24 x 30-500) is treated with the followingsolution:

Percent by weight Ammonium oleate 1.9

Water 21.0 Denatured alcohol 77.1

The excess soap solution is removed by means of squeeze rolls and thewet tissue is passed over dryer rolls, drying the tissue until it feelsdistinctly moist (10% to 15% moisture). The damp tissue is passedthrough a super-calender stack, the rolls of which are cooled. This isfollowed by a second super-calendaring operation in which heated rollsare used. It is possible to combine these operations using a stack inwhich the first half of the rolls are cooled and the remainder heated.As the tissue emerges from the hot calender rolls, it is dry and has aline finish. While its solid fraction has been increased, the calenderedpaper still retains a good proportion of its absorptiveness.

The soap-treated calendered paper is passed into a molten bath of thefollowing composition:

Per cent by weight Refined carnauba wax 34.5 Glyco wax -991 34.5 Glycowax 3-430 17.2

Paraffin (62 C. melting point) 13.8

Note: The Glyco waxes are resinous anthracene resin-like materialsmanufactured by the Glyco Products Company, of Brooklyn, N. Y. C-991 isa slightly yellowish, slightly brittle resin. 8-430 is a hard, brittle,light-colored resin.

The temperature of the melt should be about 90 C. After several secondstravel through the melt, the paper is drawn up through a set of doctorknives suitably heated to prevent crystallization of the composition onthem, one on each side of the paper, which scrape off all but aboutpounds of the melt per 100 pounds of paper. The paper then passesbetween hot rods of small diameter which smooth out the wax surface. Theimpregnated paper is allowed to cool to room temperature and then woundup. At this stage of the process, the paper is thoroughly impregnated,flexible and non-tacky, but, due to the incompatibility of the slowlycooled melt component, is so badly blushed as to be practically opaque.

The blushed paper is then unwound and passed over a head roll and downthrough an electrically heated chamber in which the impregnatedcomposition is thoroughly melted, but is not heated so hot as to harmthe paper or to vaporize the components of a the composition. While thecomposition is still in this molten state, the hot film is passed into abath of water at C. to 25 C. and then immediately out of the water. Thecontact of the film with water need be no more than one second. Thepaper is then passed between scraper rods which remove the greaterportion of the water that adheres to the surface of the him. If thepaper is running at high speed, a sheet of water is carried for somedistance vertically out of the water bath on the dim surface. It isdesirable to break this sheet of water soon and allow the greaterportion of the water to run back into the water bath. so that the smallamount of water remaining on the film can form into easily removableglobules on the surface of the film. After leaving the scraper rods. aportion of the remaining drops of water are blown or shaken from thehim. The paper then passes between felt pads or cloth-wrapped rollswhich remove the remainder of the water from the film.

The product obtained is transparent, is very clear and free from anybusiness due to blushing of the composition, is free from any haze dueto incomplete impregnation, is glossy and very dimcultly smeared orfinger-marked, is nontacky, does not stick when stored at ordinaryweather conditions in roll form or in sheets, is free from odors whichwould be objectionable for a food wrapper, is sealed by heat to a strongpermanent joint, is moistureproof, and can be printed with inks, such asare used on lacquered moistureproof, transparent regenerated cellulosesheeting.

(B) The same calendered tissue as in Example HA) is treated in the samefashion as in Example I(A) but using instead the following transparentizing composition.

Per cent by weight Candelilla wax 55.5 Ester gum (low melting) 27.8Paraflin 2 C. melting point) 10.7

If desired, the impregnated paper, after being scraped, is passeddirectly into a bath of cold water without the intervening cooling step.as described in Example I(A) The transparent product obtained is inevery way similar to that obtained in Example I(A), except that it issoftened at a slightly lower temperature. However, it is more easilyclarified by the cooling step.

(C) The same calendered tissue as in Example HA) is treated with thefollowing composition in the same manner as in Example 1(A).

Per cent by weight Refined carnauba wax 43.4 Ester gum (low melting)21.7 Glyco wax 3- 30 21.7

Paraflin (82 C. melting point) 13.2

Instead of cooling the molten composition impregnated in the tissue, thepaper is passed over polished cold iron rolls which are hollow and whichare suitably fitted for circulating cold water or brine. v

A product is obtained that is transparent, clear, glossy, moistureproofand otherwise similar to that of Example 1(A) (D) The same calenderedand soap-treated tissue as in Example HA) is impregnated and cooled inthe same manner as in Example I(A),

using, however, the i'ollowing transparentizing composition:

The product obtained is very transparent, free from haze, non-tacky,non-smeary and very excellent flexibility.

Example II (A) The same caiendered paper as in Example HA) isimpregnated with the following composition:

Solvent: Toluol Solids content: 50%

Note: I. G. wax E" is a synthetic hard wax somewhat similar to carnaubawax, prepared by esterifying Montanic acid with higher aliphaticalcohols.

Paper is impregnated with the above solution and scraped as in ExampleI(A), except that an amount of solution is left on the paper in removingthe excess such that there will be about 20 pounds of solid compositionto 100 pounds of pa.- per. In this case, the scraping knives need not beheated, since the components of the composition do not readilycrystallize out of solution during the scraping operation. It ispreferable that the impregnating solution be between 40 C. and 60 C.After leaving the scraping knives, the paper is passed through a dryingchamber at 60 C. to 90 C. in which the toluol solvent is evaporated. Theimpregnated paper is then cooled and wound up and subsequentlymomentarily exposed to an elevated temperature and chilled as in Example1(A) The product obtained will be transparent, very flexible and tough,and will have excellent heatsealing properties and good slip. It will,however, tend to blush unless chilling is carried out when thecomposition is somewhat hotter than required in the previous example.

(B) A good 20 pound glassine (24 x 36-500) is coated with a compositionof the same solid components as in Example II(A). The solvent isomitted. The solvents are not necessary in this case, since the glassineis not impregnated by such compositions and since the viscosity 0! thecomposition without the solvent is not too great for good coating.

The glasslne is passed through the molten composition and the excesscomposition is scraped off with suitable heated knives. No time isallowed for impregnation as was the case with the calendered tissues.The coated glassine is then passed over smoothing rolls and, while thecomposition is still molten, is passed into cold water. The adheringwater is removed and the film wound up.

The product obtained is moistureproof, glossy and somewhat improved intransparency. It is however. slightly hazy due to imperfections in thegiassine base. The wax coating is readily chilled to be iree from haze,since the thickness of the composition is substantially less than thatof Example II(A) The glassine base is increased in thickness about0.00005 of an inch to 0.0001 of an inch by the coating. The coatedglassine is non-tacky and non-smeary. Furthermore. it can be heat-sealedto give. a very strong Joint, even with the thin coating which isapplied.

Example III (A) A tissue of basis weight between 13 pounds and 18 pounds(24x86-500) is moistened with water to about to moisture content by anysuitable means, such as on a glassine dampener, in a suitable mistchamber or by wetting the paper and drying it down to the desiredmoisture content. The dampened paper may be rolled up and allowed tostand until the moisture is equally distributed. The uniformly moistenedpaper is calendered on hot calender rolls, during which operation it iscompacted and given a smooth surface and dried down to normal moisturecontent. The calendered paper is then transparentized by the samecomposition and process as described in Example HA).

The product obtained is moistureprooi, glossy. non-smeary, of good slip,and possesses good heatsealing properties. Its clarity and transparencywill be somewhat interior to that 01' Example HA). It will have aslightly hazy appearance, that shows up as a gray cast over a blackbackground due to somewhat poorer impregnation.

Example IV (A) A good pound glassine is coated with the followingcomposition according to the procedure outlined in Example IIiB):

Per cent by weight About 5 pounds to 10 pounds of the above compositionls applied to 100 pounds glassine.

The product obtained is moistureproof, glossy, non-smeary and non-tacky,and slightly improved in transparency. While the product is somewhathazy, since the glassine baseis not impregnated, the wax coating appliedis glass-clear. It is essential that a thin film of the abovecomposition be applied, since a thick film, such as would be obtained byimpregnating a calendered tissue as described in Example I(A) would havea slight whitish haze even with the best rapid cooling.

(B) A film of transparent regenerated cellulose sheeting, or othertransparent sheeting, such as cellulose acetate, ethyl cellulose,gelatin, etc., about 0.001 of an inch thick is coated as in ExampleIV(A). Between 5 pounds and 10 pounds of wax composition per 100 poundsfilm is applied.

The product obtained is moistureproof, glossy, non-smeary, non-taclw andglass-clear. The wax coating is tough and flexible. The film can becrumpled without chipping ofl portions of the coating or leavingobjectionable marks or fractures in the coating.

Since it is obvious that various changes and modifications may be madein the above description without departing from the nature or spiritthereof, this invention is not restricted thereto, except as set forthin the appended claims.

We claim:

1. A method which comprises applying a moistureprooflng composition inthe molten state and comprising a moistureprooflng wax, a hard wax and ablending agent preventing separation of the waxes and inhibiting theproduction of haziness in the composition when chilled to a selectedbase and rapidly chilling the treated base as some stage of the processwhen the composition is in the molten condition and beforecrystallization has begun, whereby a glass-clear transparent andmoistureproof coating is obtained.

2. A method which comprises impregnating a thin, porous paper with amoistureprooflng composition in the molten state and comprising amoistureprooflng wax, a hard wax and a blending agent preventingseparation of the waxes and inhibiting the production of haziness in thecom position when chilled and rapidly chilling the impregnated paperat'some stage of the process when the composition is in the moltencondition and before crystallization has begun. whereby a transparent,moistureproof and flexible product is obtained.

3. A method which comprises incorporating a wetting agent in a thin,porous paper, calendering said paper, impregnating the thus-treatedpaper with a moistureprooflng composition in the molten state andcomprising a moistureprooflng wax, a hard wax and a blending agentpreventing separation of the waxes and inhibiting the production ofhaziness in the composition when chilled and rapidly chilling theimpregnated paper at some state of the process when the composition isstill in the molten condition and before crystallization has begun,whereby a transparent, moistureprooi' and flexible product is obtained.

4. A method which comprises applying a moistureprooflng composition inthe molten state and comprising a moistureprooflng wax, a hard wax and ablending agent preventing separation of the waxes and inhibiting theproduction of haziness in the composition when chilled to a selectedbase and rapidly chilling the treated base at some stage of the processwhen the composition is in the molten condition and beforecrystallization has begun by immersion in cold water, whereby aglass-clear transparent and moistureproof coating is obtained.

5. A method which comprises impregnating a thin, porous paper with amoistureprooflng composition in the molten state and comprising amoistureprooflng wax, a hard wax and a blending agent preventingseparation of the waxes and inhibiting the production of haziness in thecomposition when chilled and rapidly chilling the impregnated paper atsome stage of the process when the composition is in the moltencondition and before crystallization has begun by immersion in coldwater, whereby a transparent, moistureproof and flexible product isobtained.

6. A method which comprises incorporating a wetting agent in a thin,porous paper, calendering said paper, impregnating the thus-treatedpaper with a moistureprooflng composition in the molten state andcomprising a moistureprooflng wax, a hard wax and a blending agentpreventing separation of the waxes and inhibiting the production ofhaziness in the composition when chilled and rapidly chilling theimpregnated paper at some stage of the process when the composition isstill in the molten condition and before crystallization has begun byimmersion in cold water, whereby a transparent, moistureprooi' andflexible product is obtained.

7. A method which comprises applying a moistureprooflng composition inthe molten state and comprising 2% to 30% of a moistureprooflng waxysubstance, 20% to 80% of a hard wax and 20% to 80% of a blending agentpreventing separation of the waxes and inhibiting the production ofhaziness in the composition when chilled, the percentages being byweight, to a selected base and rapidly chilling the treated base at somestage in the process when the composition is in the molten condition andbefore crystallization has begun, whereby a glass-clear transparent andmoistureproof coating is obtained.

8. An article of manufacture produced by the process of claim 1comprising highly calendered, thin paper having on each side thereof aglassclear transparent moistureproof coating consisting essentially of amoistureprooflng waxy substance, a hard wax and a blending agentpreventing separation of the waxes and inhibiting the production ofhaziness in the composi ion when chilled, the ingredients being presentin such relative proportions as to produce a glassclear transparent,glossy, moistureprooi coating and to materially improve the transparencyof the paper base.

9. An article of manufacture produced by the process of claim 2comprising highly calendered, thin, porous paper impregnated and coatedwith a composition consisting essentially of 2. moistureprooring waxysubstance, a hard wax and a blending agent preventing separation of thewaxes and inhibiting the production of haziness, the ingredients beingpresent in such relative proportions as to transparentize the paper andproduce a transparent and moistureproof prodnot.

10. An article of manufacture produced by the process of claim 3comprising highly calendered, thin, porous paper having a wetting agentincorporated therein and impregnated and coated with a compositionconsisting essentially of a moistureprooflng waxy substance, a hard waxand a blending agent preventing separation of the waxes and inhibitingthe production of haziness, the ingredients being present in suchrelative proportions as to transparentize the paper and produce atransparent and moistureproof product.

11. An article of manufacture produced by the process of claim 2comprising highly calendered, thin, porous paper impregnated and coatedwith a composition having an index of refraction approximately the sameas cellulose and consisting essentially of a moistureprooflng waxysubstance, a hard wax and a blending agent preventing separation of thewaxes and inhibiting the production of haziness, the ingredients beingpresent in such relative proportions as to transparentize the paper andproduce a transparent and moistureproof product.

12. An article of manufacture produced by the process of claim 3comprising highly calendered, thin, porous paper having a wetting agentincorporated therein and impregnated and coated with a compositionhaving an index of refraction approximately the same as cellulose andconsisting essentially of a moistureprooflng waxy substance, a hard waxand a blending agent preventing separation of the waxes and inhibitingthe production of haziness, the ingredients being present in suchrelative proportions as to transparentise'the paper and produce atransparent and moistureproof product.

13. An article of manufacture produced by the process of claim 1comprising glassine paper having on each side thereof a glass-cleartransparent moistureproof coating consisting essentially oi amoistureprooflng waxy substance, a hard wax and a blending agentpreventing separation of the waxes and inhibiting the production ofhaziness, the ingredients being present in such relative proportions asto produce a glass-clear transparent, glossy moistureproof coating andto materially improve the transparency of the paper base.

14. An article of manufacture produced by the process of claim 1comprising highly calendered, thin paper having on each side thereof aglassclear transparent moistureproof coating consisting essentially of2% to 30% of a moistureproofing waxy substance, 20% to of a hard wax,and 20% to 80% of a blending agent preventing separation of the waxesand inhibiting the production of haziness, the percentages being byweight and the ingredients being present in such relative proportions asto produce a glass-clear transparent, glossy moistureproof coating andto materially improve the transparency of the paper base.

15. An article of manufacture produced by the process of claim 1comprising highly calendered, thin, porous paper impregnated and coatedwith a composition consisting essentially of 2% to 30% of amoistureproofing waxy substance, 20% to 80% of a hard wax, and 20% to80% of a blending agent preventing separation of the waxes andinhibiting the production of haziness, the percentages being by weightand the ingredients being present in such relative proportions as totransparentize the paper and produce a transparent and moistureproofproduct.

16. An article of manufacture produced by the process of claim 3comprising highly calendered, thin, porous paper having a wetting agentincorporated therein and impregnated and coated with a compositionconsisting essentially of 2% to 80% of a moistureprooflng waxysubstance, 20% to 80% of a hard wax, and 20% to 80% of a blending agentpreventing separation of the waxes and inhibiting the production ofhazinees, the percentages being by weight and the ingredients beingpresent in such relative proportions as to transparentine the paper andproduce a transparent and moistureproof product.

1'1. An article of manufacture produced by the process of claim 1comprising highly calendered, thin. porous paper impregnated and coatedwith a composition having an index of refraction approximately the sameas cellulose and consisting essentially of 2% to 30% of amoistureproonng waxy substance. 20% to 80% of a hard wax, and 20% to 80%of a blending agent preventing separation of the waxes and inhibitingthe production of haziness, the percentages being by weight and theingredients being present in such relative proportions as totransparentize the paper and produce a transparent and moistureproofproduct.

18. An article of manufacture produced by the process of claim 3comprising highly calendered, thin, porous paper having a wetting agentincorporated therein and impregnated and coated with a compositionhaving an index of refraction approximately the same as cellulose andconsisting essentially of 2% to 30% of a moistureprooflng waxysubstance, 20% to 80% of a hard wax, and 20% to 80% of a blending agentpreventing separation of the waxes and inhibiting the production ofhaziness, the percentages being by weight and the ingredients beingpresent in such relative proportions as to transparentize the paper andproduce a transparent and moistureproof product.

19. An article of manufacture produced by the process of claim 1comprising glassine paper having on each side thereof a glass-cleartransparent moistureproof coating consisting essentially of 2% to 30% ofa moistureproofing waxy substance, 20% to 80% of a hard wax, and 20% to80% of a blending agent preventing separation of the waxes andinhibiting the production of haziness, the percentages being by weightand the ingredients being present in such relative proportions as toproduce a glass-clear transparent, glossy moistureproof coating and tomaterially improve the transparency of the paper base.

'I'HERON G. FINZEL. DONALD E. DREW.

CERTIFICATE OF CORRECTION.

Reissue No. 20,8l September 6, 1.755.

THERON G. FINZEL, AL.

It is hereby certified that error appears in the printed specificationof the above mmbered patent requiring correctiones follows: Page J firstcolmnn, line 10, for as read are; page 6, first column, line 8, claim 1,for the word "as read at; and that the said Letters Patent should beread with this correction therein that the same may conform tothe recordof the case in the Patent Office.

Signed and sealed this 25th day of October, A. D. 1938.

Henry Van Aredale (Seal) Acting Commissioner of Patents.

